HR: 1340h
AN: U43A-0822    [Abstracts]
TI: Geochronology and geochemistry of volcanic glasses associated with early Homo sapiens in Ethiopia.
AU: * Morgan, L E
EM: lmorgan@berkeley.edu
AF: Dept. of Earth & Planetary Science, UC Berkeley, 307 McCone Hall #4767, Berkeley, CA 94720-4767 United States
AU: Renne, P R
EM: prenne@bgc.org
AF: Dept. of Earth & Planetary Science, UC Berkeley, 307 McCone Hall #4767, Berkeley, CA 94720-4767 United States
AU: Renne, P R
EM: prenne@bgc.org
AF: Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, CA 94709 United States
AU: WoldeGabriel, G
EM: wgiday@lanl.gov
AF: Los Alamos National Laboratory, Earth Environmental Sciences, Los Alamos National Lab P.O. Box 1663, Los Alamos, NM 87545 United States
AU: White, T D
EM: timwhite@berkeley.edu
AF: Integrative Biology, UC Berkeley, 3060 Valley Life Sciences Building #3140, Berkeley, CA 94720-3140 United States
AB: In past work at hominid sites in Ethiopia, ⁴⁰Ar/³⁹Ar dating was used to constrain obsidian from the base of the Upper Herto Member of the Bouri Formation to 160 ± 2 ka. An overlying vitric tuff was then geochemically correlated to one from the Konso region of Ethiopia, which is constrained to be older than 154 ± 7 ka, thus leaving only 6 ± 7 ky between eruption and deposition of the fossils and artifacts at Herto. To continue these studies, we have collected and are currently analyzing obsidian and associated volcanic ashes from Middle Stone Age (MSA) archaeological and paleontological sites in the Middle Awash, Ethiopia. Distinctive geochemical signatures among most obsidian fragments collected (n=20 per site) suggest that obsidian was being derived from a variety of sources. By comparing our geochemical data with that from known obsidian deposits in Ethiopia and elsewhere in East Africa, we hope to determine the source localities for the obsidian and thus gauge the extent of trade networks during the MSA. Thus, by characterizing obsidian using both ⁴⁰Ar/³⁹Ar geochronology and trace element geochemistry, will make it possible to temporally refine the stratigraphy and prehistory at hominid sites, which in turn improves understanding of hominid behavior and evolution.
DE: 1065 Major and trace element geochemistry
DE: 1105 Quaternary geochronology
DE: 1145 Tephrochronology (8455)
DE: 9305 Africa
SC: Union [U]
MN: Fall Meeting 2005